Some interesting books on SOA topics you should own

• SOA Principles of Service Design, Thomas Erl
• Enterprise SOA. Best Practices für Serviceorientierte Architekturen - Einführung, Umsetzung, Praxis, Dirk Krafzig
• SOA in Practice: The Art of Distributed System Design
• Enterprise Integration Patterns: Designing, Building, and Deploying Messaging Solutions, Gregor Hohpe
• Enterprise Service Bus. Theory in Practice, David A. Chappell